This application is related to the following co-pending U.S. patent applications Ser. No. 08/554,042 for "HAND-HELD ELECTRONIC PRINTER" filed on Nov. 6, 1995; and Ser. No. 08/554,043 for "HAND-HELD SWEEP ELECTRONIC PRINTER" filed on Nov. 6, 1995; the entire disclosures of which are fully incorporated herein by reference.
The invention relates generally to methods and apparatus for scanning or reading an image from a portion of a document, such as lines of text and images. More particularly, the invention relates to fully self contained and hand-held scanning apparatus that is operated, for example, using a sweeping motion of the apparatus across a selectable area of a document.
Hand-held scanners known heretofore have used external apparatus, such as a personal computer, for example, to receive, store, and process image information, and can exhibit considerable image distortion. This distortion arises from movement of the scan head along a nonlinear path. Additionally, in a hand controlled scanning device, it is possible to rotate the scan head such as by a pivoting action brought about by the natural tendency of an operator to allow the apparatus to tilt or rotate during a sweeping movement. This pivoting action changes the orientation of the scan head with respect to the document and thus can further result in distortion of the scanned image. In some cases, mechanical devices have been incorporated into the scanner to restrict or constrain movement to a linear path and to reduce the occurrence of a pivoting or rotational motion imparted to the apparatus. Such devices are less than desirable as the mechanical constraints reduce the flexibility of the apparatus, increase the apparatus size and weight, and restrict use of the scanner to flat surfaces. Therefore, information cannot be read from a three-dimensional object such as a book. Further, such devices typically block ambient illumination and require a supplemental light source to be built into the apparatus, increasing power requirements.
The objectives exist, therefore, for providing a more convenient apparatus and methods for a hand-held and operated fully self contained scanner that is responsive to a simple and unconstrained sweeping motion that exhibits reduced distortion in the recorded image caused by such sweeping motion, and that generally requires only ambient illumination.